It is well known that traditional surgical procedures in locations deep within a patient's body require a long incision, extensive muscle stripping, prolonged retraction of muscles for visualization, and denervation and devascularization of the adjacent tissue. These procedures result in extensive tissue traumatization and consequently in prolonged recovery time, risk of infections, high hospitalization costs, pain that can be more severe than the pain due to the initial ailment, and in some cases permanent scarring. The current state of the art for minimally invasive surgical procedures utilizes cylindrical tubes, cannulas, or blades to access locations deep in the patient's body. The use of these access devices rather than a long incision causes fewer traumas to the adjacent tissue, reduces the recovery time and pain and may be performed in some cases under only local anesthesia. The potential for the avoidance of general anesthesia reduces post-operative recovery time and the risk of complications.
Minimally invasive surgical procedures are especially desirable for spine surgeries because spine pathologies are located deep within the body without clear muscle planes and there is danger of damaging the adjacent neural and vascular tissues. In treating the majority of spinal pathologies, the spinal muscles are stripped from the bony elements of the spine followed by laminectomy or discectomy to expose the dura, the nerve roots, and the discs. The incision has to be wide enough and the tissues have to be retracted to maintain a channel from the skin to the floor of the spinal canal that will allow direct visualization. Laminectomy or discectomy is usually followed by spine stabilization or fusion. Spine stabilization involves implantation of pedicle screws in the pedicles and securing of rods or plates to the pedicles screws, as described in U.S. Pat. No. 6,626,909, the contents of which are incorporated herein by reference. The destruction to the spinal structures is even more extensive during the spine stabilization procedures, which require more lateral tissue dissection and exposure to access the transverse processes and pedicles for placement of pedicle screws, rod constructs for stability, and bone graft under direct vision.
Furthermore, in spine stabilization procedures, connecting elements, such as rods, plates or wires are placed and fixed between two or more locations of the spine. Placement of these connecting elements requires open surgery, which is currently one of the major limitations of other percutaneous access methodologies. Accordingly there is a need for inserting and placing these connecting elements between two or more separate spinal locations without performing open surgery. The emerging percutaneous access systems that address some of the limitations of open surgeries are limited to cylindrical tubes, cannulas, or blades. One of the shared limitations of these systems is that they all have solid walls which in our experience tend to reduce visualization of the deep structures and require specific alignment of a predefined access slot. Accordingly, there is a need for a percutaneous access system that allows visualization of the deep structures and does not require specific alignment.